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<p style='font-family: monospace;font-size:small'>26 February 2004</p>
</div>
<div class='div1'><a name='XPath'></a>
<h1 id='XPath-h1' class='div1'>1.
Document Object Model XPath</h1><dl>
<dt><i>Editor</i>:
</dt><dd>Ray Whitmer, Netscape/AOL</dd>
</dl>
<div class='noprint'>
<h2 id='table-of-contents'>Table of contents</h2>
<ul class='toc'>
<li class='tocline3'><a class='tocxref' href='#Introduction'>1.1 Introduction</a>
</li>
<li class='tocline3'><a class='tocxref' href='#Mapping'>1.2 Mapping DOM to XPath</a>
<ul class='toc'>
<li class='tocline4'><a class='tocxref' href='#ElementNodes'>1.2.1 Element Nodes</a>
<li class='tocline4'><a class='tocxref' href='#AttributeNodes'>1.2.2 Attribute Nodes</a>
<li class='tocline4'><a class='tocxref' href='#NamespaceNodes'>1.2.3 Namespace Nodes</a>
<li class='tocline4'><a class='tocxref' href='#TextNodes'>1.2.4 Text Nodes</a>
<li class='tocline4'><a class='tocxref' href='#EntityReferences'>1.2.5 Entity Reference Nodes</a>
<li class='tocline4'><a class='tocxref' href='#CommentNodes'>1.2.6 Comment Nodes</a>
<li class='tocline4'><a class='tocxref' href='#PINodes'>1.2.7 Processing Instruction Nodes</a>
<li class='tocline4'><a class='tocxref' href='#DocumentOrder'>1.2.8 Document order</a>
</ul></li>
<li class='tocline3'><a class='tocxref' href='#Conformance'>1.3 Conformance</a>
</li>
<li class='tocline3'><a class='tocxref' href='#Interfaces'>1.4 Interfaces</a>
<ul class='toc'>
<li class='tocline4'><a href='#XPathException'>XPathException</a>,
<a href='#XPathExceptionCode'>XPathExceptionCode</a>,
<a href='#XPathEvaluator'>XPathEvaluator</a>,
<a href='#XPathExpression'>XPathExpression</a>,
<a href='#XPathNSResolver'>XPathNSResolver</a>,
<a href='#XPathResult'>XPathResult</a>,
<a href='#XPathNamespace'>XPathNamespace</a></ul></li>
</ul>
</div>
<div class='div2'><a name='Introduction'></a>
<h2 id='Introduction-h2' class='div2'>1.1
Introduction</h2><p>
XPath 1.0 [<cite><a class='noxref normative' href='references.html#XPath10'>XPath 1.0</a></cite>] is becoming an important part of a
variety of many specifications including XForms, XPointer, XSL, XML
Query, and so on. It is also a clear advantage for user applications
which use DOM to be able to use XPath expressions to locate nodes
automatically and declaratively. <p>
This specification was created to map between the Document Object
Model's representation of the W3C Information Set and XPath's
<a href='glossary.html#dt-model'>model</a> to permit XPath functions to be
supplied and results returned within the framework of DOM
<a href='glossary.html#dt-API'>API</a>s in a standard, interoperable way,
allowing also for <a href='glossary.html#dt-live'>liveness</a> of data,
which is not addressed by the XPath specification but is present in
results coming from the DOM hierarchy.
</div> <!-- div2 Introduction -->
<div class='div2'><a name='Mapping'></a>
<h2 id='Mapping-h2' class='div2'>1.2
Mapping DOM to XPath</h2><p>This section presents a mapping between the Document Object Model
[<cite><a class='noxref normative' href='references.html#DOM2Core'>DOM Level 2 Core</a></cite>] and the XPath 1.0 [<cite><a class='noxref normative' href='references.html#XPath10'>XPath 1.0</a></cite>]
model for the purposes of implementing the APIs.
<div class='div3'><a name='ElementNodes'></a>
<h3 id='ElementNodes-h3' class='div3'>1.2.1
Element Nodes</h3><p>The DOM model uses <code>Element</code> nodes to represent <a class='normative' href='http://www.w3.org/TR/2004/REC-xml-infoset-20040204/#infoitem.element'><em>Element Information Items</em></a>.
These nodes of a document are directly used to represent the elements of
an XPath result.</div> <!-- div3 ElementNodes -->
<div class='div3'><a name='AttributeNodes'></a>
<h3 id='AttributeNodes-h3' class='div3'>1.2.2
Attribute Nodes</h3><p>The DOM model uses <code>Attr</code> nodes to represent <a class='normative' href='http://www.w3.org/TR/2004/REC-xml-infoset-20040204/#infoitem.attribute'><em>Attribute Information
Items</em></a> of attribute and namespace attribute
properties of <a class='normative' href='http://www.w3.org/TR/2004/REC-xml-infoset-20040204/#infoitem.element'><em>Element
Information Item</em></a>. These nodes have no parent, but
have an <code>ownerElement</code> which can be used as XPath
defines an attribute's parent.<p>XPath 1.0 does not make available the namespace attributes of an
element. The DOM implementation of XPath 1.0 using these defined
interfaces never directly returns <code>Attr</code> nodes of namespace
attributes, but returned <code>Element</code> nodes still contain them.</div> <!-- div3 AttributeNodes -->
<div class='div3'><a name='NamespaceNodes'></a>
<h3 id='NamespaceNodes-h3' class='div3'>1.2.3
Namespace Nodes</h3><p>The XPath model expects namespace nodes for each in-scope namespace to
be attached to each <a href='glossary.html#dt-element'>element</a>. DOM only
maintains the namespace attributes instead of replicating in-scope
namespaces on each <code>Element</code> where they are in-scope. The DOM
implementation of XPath produces a new node of type
<code>XPATH_NAMESPACE_NODE</code>, defined in the
<a href='xpath.html#XPathNamespace'><code>XPathNamespace</code></a> interface, to properly preserve identity and
ordering in a way that is compatible with XPath. This node type is only
visible using the XPath evaluation methods.<p>The set of in-scope namespaces of an element is the default xml
namespace combined with the contributions of namespace attributes of the
current and all ancestor elements. In addition to explicit namespace
attributes, any element has an implicit declaration of its own prefix,
if any, or if no prefix then of the default namespace, which is enforced
during namespace serialization, fixup, and lookup, which must be added to
the set of in-scope namespaces when generating namespace nodes for an
element. This causes the set of namespace nodes to be consistent with
serialization, fixup, and lookup of namespaces in DOM Level 3.
</div> <!-- div3 NamespaceNodes -->
<div class='div3'><a name='TextNodes'></a>
<h3 id='TextNodes-h3' class='div3'>1.2.4
Text Nodes</h3><p>The XPath model relies on the XML Information Set [<cite><a class='noxref normative' href='references.html#InfoSet'>XML Information Set</a></cite>] ands represents <a class='normative' href='http://www.w3.org/TR/2004/REC-xml-infoset-20040204/#infoitem.character'><em>Character Information
Items</em></a> in a single logical text node where DOM may have
multiple fragmented <code>Text</code> nodes due to cdata sections, entity
references, etc. Instead of returning multiple nodes where XPath sees a
single logical text node, only the first non-empty DOM <code>Text</code>
or <code>CDATASection</code> node of any logical XPath text will be
returned in the node set. Applications using XPath in an environment
with fragmented text nodes must manually gather the text of a single
logical text node possibly from multiple nodes beginning with the first
<code>Text</code> node or <code>CDATASection</code> node returned by the
implementation.<p><b>Note:</b> In an attempt to better implement the XML Information Set, DOM Level
3 Core [<cite><a class='noxref informative' href='references.html#DOMCore'>DOM Level 3 Core</a></cite>] adds the attribute
<code>wholeText</code> on the <code>Text</code> interface for
retrieving the whole text for <a href='glossary.html#dt-logically-adjacent-text-nodes'>logically-adjacent Text
nodes</a> and the method <code>replaceWholeText</code> for
replacing those nodes.</p>
</div> <!-- div3 TextNodes -->
<div class='div3'><a name='EntityReferences'></a>
<h3 id='EntityReferences-h3' class='div3'>1.2.5
Entity Reference Nodes</h3><p>The DOM model may represent <a class='normative' href='http://www.w3.org/TR/2004/REC-xml-infoset-20040204/#infoitem.rse'><em>Unexpanded Entity Reference
Information Items</em></a> or may provide the position and URI of
expanded entity hierarchies by using <code>EntityReference</code> nodes.
XPath 1.0 does not preserve corresponding information.<p>Where the node represents an unexpanded entity reference, it is
skipped as dictated by the XPath specifications for all infoset items
besides those specifically processed.<p>Where there is a hierarchy underneath the node, these nodes are
processed as though they were siblings of the entity reference, as
is consistent with the rest of the DOM specification.<p><code>EntityReference</code> nodes found within a DOM hierarchy are
never returned as a node of the result, but returned nodes may contain
or be contained within an <code>EntityReference</code> node. Text may be
split partially inside and partially outside of an
<code>EntityReference</code> node, but this is solved by handling
<code>Text</code> nodes as described in the previous section.</div> <!-- div3 EntityReferences -->
<div class='div3'><a name='CommentNodes'></a>
<h3 id='CommentNodes-h3' class='div3'>1.2.6
Comment Nodes</h3><p>The DOM model uses <code>Comment</code> nodes to represent <a class='normative' href='http://www.w3.org/TR/2004/REC-xml-infoset-20040204/#infoitem.comment'><em>Comment Information Items</em></a>.
These nodes of a document are directly used to represent the comments of
an XPath result.</div> <!-- div3 CommentNodes -->
<div class='div3'><a name='PINodes'></a>
<h3 id='PINodes-h3' class='div3'>1.2.7
Processing Instruction Nodes</h3><p>The DOM model uses <code>ProcessingInstruction</code> nodes to
represent <a class='normative' href='http://www.w3.org/TR/2004/REC-xml-infoset-20040204/#infoitem.pi'><em>Processing Instruction
Information Items</em></a>. These nodes of a document are directly used
to represent the processing instructions of an XPath result.</div> <!-- div3 PINodes -->
<div class='div3'><a name='DocumentOrder'></a>
<h3 id='DocumentOrder-h3' class='div3'>1.2.8
Document order</h3><p>The <a href='glossary.html#dt-document-order'>document order</a> of nodes
in the DOM Core has been defined to be compatible with the <a class='normative' href='http://www.w3.org/TR/1999/REC-xpath-19991116#dt-document-order'><em>XPath document order</em></a>.
The XPath DOM extends the document order of the DOM Core to include
the <a href='xpath.html#XPathNamespace'><code>XPathNamespace</code></a> nodes. Element nodes occur before their
children. The attribute nodes and namespace nodes of an element occur
before the children of the element. The namespace nodes are defined to
occur before the attribute nodes. The relative order of namespace nodes
is implementation-dependent. The relative order of attribute nodes is
implementation-dependent. The <code>compareTreePosition</code> method on
the <code>Node</code> interface defined in the DOM Core must compare the
<a class='noxref' href='xpath.html#XPathNamespace'><code>XPathNamespace</code></a> nodes using this extended document order if
the XPath DOM module is supported.<p><b>Note:</b> It is possible that in future versions of XPath, the order of namespace
nodes or other aspects of document order may change incompatibly.</p>
</div> <!-- div3 DocumentOrder --></div> <!-- div2 Mapping -->
<div class='div2'><a name='Conformance'></a>
<h2 id='Conformance-h2' class='div2'>1.3
Conformance</h2><p>This section explains conformance to DOM Level 3 XPath Module.<p>A DOM implementation must not return <code>true</code> to
<code>hasFeature("xpath", "3.0")</code> unless the implementation
conforms to that module. As documented in [<cite><a class='noxref informative' href='references.html#DOMCore'>DOM Level 3 Core</a></cite>], if a <code>null</code> or empty string is
passed in for the second parameter, then conformance is still
required to some version of the DOM XPath Module or
<code>false</code> must be returned.<p>A conformant
implementation is DOM Level 3 XPath must support all the interfaces
as specified in that specification. In addition to implementing the
interfaces in the DOM XPath Module, a conforming implementation must
correctly implement each part of the XPath 1.0 specification when
evaluating expressions including Location Paths, Expressions, the
Core Function Library, and the mapping between DOM and the XPath 1.0
data model described in the DOM Level 3 XPath Module. The XPath
<code>id()</code>function must return the corresponding element, if
any, returned by the DOM method
<code>Document.getElementById</code>.<p>After meeting the
requirements for conformance, a conforming implementation may
implement additional functions and variables. Applications which
evaluate expressions using these extensions will not necessarily be
portable to other implementations of the DOM Level 3 XPath
Module.</div> <!-- div2 Conformance -->
<div class='div2'><a name='Interfaces'></a>
<h2 id='Interfaces-h2' class='div2'>1.4
Interfaces</h2><p>
An implementation is DOM Level 3 XPath conformant if it supports
the Core module defined in [<cite><a class='noxref normative' href='references.html#DOM2Core'>DOM Level 2 Core</a></cite>] and the module
defined in this specification. An implementation conforms to a DOM
module if it supports all the interfaces for that module and the
associated semantics.
<p>
A DOM application may use the <code>hasFeature(feature,
version)</code> method of the <code>DOMImplementation</code>
interface with parameter values "XPath" and "3.0" (respectively)
to determine whether or not the XPath module is supported by the
implementation. In order to fully support this module, an
implementation must also support the "Core" feature defined in the
DOM Level 2 Core specification [<cite><a class='noxref normative' href='references.html#DOM2Core'>DOM Level 2 Core</a></cite>].
<p>
A DOM implementation must not return <code>true</code> to the
<code>hasFeature(feature, version)</code> method of the
DOMImplementation interface for that feature unless the
implementation conforms to that module. The version number for the
feature used in this document is <code>"3.0"</code>.
<dl><dt><b>Exception <i><a name='XPathException'>XPathException</a></i></b></dt>
<dd>
<p>A new exception has been created for exceptions specific
to these XPath interfaces.
<dl>
<dt><br><b>IDL Definition</b></dt>
<dd>
<div class='idl-code'>
<pre>
exception <a class='noxref' href='xpath.html#XPathException'>XPathException</a> {
unsigned short code;
};
// XPathExceptionCode
const unsigned short <a class='noxref' href='xpath.html#INVALID_EXPRESSION_ERR'>INVALID_EXPRESSION_ERR</a> = 51;
const unsigned short <a class='noxref' href='xpath.html#TYPE_ERR'>TYPE_ERR</a> = 52;
</pre>
</div><br>
</dd>
<dt><b>Definition group <i><a name='XPathExceptionCode'>XPathExceptionCode</a></i></b></dt>
<dd><dl>
<dt><b>Defined Constants</b></dt>
<dd><dl>
<dt><a name='INVALID_EXPRESSION_ERR'><code class='constant-name'>INVALID_EXPRESSION_ERR</code></a></dt><dd>
If the expression has a syntax error or otherwise is not a legal
expression according to the rules of the specific
<a href='xpath.html#XPathEvaluator'><code>XPathEvaluator</code></a> or contains specialized extension functions
or variables not supported by this implementation.</dd>
<dt><a name='TYPE_ERR'><code class='constant-name'>TYPE_ERR</code></a></dt><dd>
If the expression cannot be converted to return the specified type.</dd>
</dl>
</dd></dl>
</dd>
</dl></dd>
<dt><b>Interface <i><a name='XPathEvaluator'>XPathEvaluator</a></i></b></dt>
<dd>
<p>
The evaluation of XPath expressions is provided by
<code>XPathEvaluator</code>. In a DOM
implementation which supports the XPath 3.0 feature, as described
above, the <code>XPathEvaluator</code> interface will be implemented
on the same object which implements the <code>Document</code>
interface permitting it to be obtained by the usual binding-specific
method such as casting or by using the DOM Level 3 getInterface method.
In this case the implementation obtained from the Document supports the
XPath DOM module and is compatible with the XPath 1.0 specification. <p>Evaluation of expressions with specialized extension functions or
variables may not work in all implementations and is, therefore, not
portable. <code>XPathEvaluator</code> implementations may be available
from other sources that could provide specific support for specialized
extension functions or variables as would be defined by other
specifications.
<dl>
<dt><br><b>IDL Definition</b></dt>
<dd>
<div class='idl-code'>
<pre>
interface <a class='noxref' href='xpath.html#XPathEvaluator'>XPathEvaluator</a> {
<a class='noxref' href='xpath.html#XPathExpression'>XPathExpression</a> <a class='noxref' href='xpath.html#XPathEvaluator-createExpression'>createExpression</a>(in DOMString expression,
in <a class='noxref' href='xpath.html#XPathNSResolver'>XPathNSResolver</a> resolver)
raises(<a class='noxref' href='xpath.html#XPathException'>XPathException</a>,
DOMException);
<a class='noxref' href='xpath.html#XPathNSResolver'>XPathNSResolver</a> <a class='noxref' href='xpath.html#XPathEvaluator-createNSResolver'>createNSResolver</a>(in Node nodeResolver);
DOMObject <a class='noxref' href='xpath.html#XPathEvaluator-evaluate'>evaluate</a>(in DOMString expression,
in Node contextNode,
in <a class='noxref' href='xpath.html#XPathNSResolver'>XPathNSResolver</a> resolver,
in unsigned short type,
in DOMObject result)
raises(<a class='noxref' href='xpath.html#XPathException'>XPathException</a>,
DOMException);
};
</pre>
</div><br>
</dd>
<dt><b>Methods</b></dt>
<dd><dl>
<dt><code class='method-name'><a name='XPathEvaluator-createExpression'>createExpression</a></code></dt>
<dd>
<div class='method'>
Creates a parsed XPath expression with resolved namespaces.
This is useful when an expression will be reused in an application
since it makes it possible to compile the expression string into a
more efficient internal form and preresolve all <a href='glossary.html#dt-namespaceprefix'>namespace prefixes</a> which occur
within the expression.<div class='parameters'>
<b>Parameters</b>
<div class='paramtable'>
<dl>
<dt><code class='parameter-name'>expression</code> of type
<code>DOMString</code></dt><dd>
The XPath expression string to be parsed.<br>
</dd>
<dt><code class='parameter-name'>resolver</code> of type
<a href='xpath.html#XPathNSResolver'><code>XPathNSResolver</code></a></dt><dd>
The <code>resolver</code> permits translation of all
prefixes, including the <code>xml</code> namespace prefix,
within the XPath expression into appropriate <a href='glossary.html#dt-namespaceURI'>namespace URIs</a>. If this is
specified as <code>null</code>, any <a href='glossary.html#dt-namespaceprefix'>namespace prefix</a> within the
expression will result in <code>DOMException</code> being
thrown with the code <code>NAMESPACE_ERR</code>.<br>
</dd>
</dl>
</div></div> <!-- parameters -->
<div class='return'>
<b>Return Value</b>
<div class='returntable'>
<table summary='Layout table: the first cell contains
the type of the return value, the second contains a short description'
border='0'><tr><td valign='top'><p><a href='xpath.html#XPathExpression'><code>XPathExpression</code></a></p></td><td>
<p>
The compiled form of the XPath expression.</td></tr></table>
</div></div> <!-- return -->
<div class='exceptions'>
<b>Exceptions</b>
<div class='exceptiontable'>
<table summary='Layout table: the first cell contains
the type of the exception, the second contains
the specific error code and a short description'
border='0'>
<tr><td valign='top'><p><a href='xpath.html#XPathException'><code>XPathException</code></a></p></td><td>
<p>INVALID_EXPRESSION_ERR: Raised if the expression is not
legal according to the rules of the
<code>XPathEvaluator</code>.</td></tr>
<tr><td valign='top'><p><code>DOMException</code></p></td><td>
<p>NAMESPACE_ERR: Raised if the expression contains
<a href='glossary.html#dt-namespaceprefix'>namespace prefixes</a>
which cannot be resolved by the specified
<a href='xpath.html#XPathNSResolver'><code>XPathNSResolver</code></a>.</td></tr>
</table>
</div></div> <!-- exceptions -->
</div> <!-- method -->
</dd>
<dt><code class='method-name'><a name='XPathEvaluator-createNSResolver'>createNSResolver</a></code></dt>
<dd>
<div class='method'>
Adapts any DOM node to resolve namespaces so that an XPath
expression can be easily evaluated relative to the context of
the node where it appeared within the document. This adapter
works like the DOM Level 3 method <code>lookupNamespaceURI</code>
on nodes in resolving the namespaceURI from a given prefix
using the current information available in the node's
hierarchy at the time lookupNamespaceURI is called. also
correctly resolving the implicit xml prefix.<div class='parameters'>
<b>Parameters</b>
<div class='paramtable'>
<dl>
<dt><code class='parameter-name'>nodeResolver</code> of type
<code>Node</code></dt><dd>
The node to be used as a context for namespace resolution.<br>
</dd>
</dl>
</div></div> <!-- parameters -->
<div class='return'>
<b>Return Value</b>
<div class='returntable'>
<table summary='Layout table: the first cell contains
the type of the return value, the second contains a short description'
border='0'><tr><td valign='top'><p><a href='xpath.html#XPathNSResolver'><code>XPathNSResolver</code></a></p></td><td>
<p>
<a class='noxref' href='xpath.html#XPathNSResolver'><code>XPathNSResolver</code></a> which resolves namespaces with respect to
the definitions in scope for a specified node.</td></tr></table>
</div></div> <!-- return -->
<div><b>No Exceptions</b></div>
</div> <!-- method -->
</dd>
<dt><code class='method-name'><a name='XPathEvaluator-evaluate'>evaluate</a></code></dt>
<dd>
<div class='method'>
Evaluates an XPath expression string and returns a result of the
specified type if possible.<div class='parameters'>
<b>Parameters</b>
<div class='paramtable'>
<dl>
<dt><code class='parameter-name'>expression</code> of type
<code>DOMString</code></dt><dd>
The XPath expression string to be parsed and evaluated.<br>
</dd>
<dt><code class='parameter-name'>contextNode</code> of type
<code>Node</code></dt><dd>
The <code>context</code> is context node for the evaluation
of this XPath expression. If the XPathEvaluator was obtained
by casting the <code>Document</code> then this must be owned by
the same document and must be a <code>Document</code>,
<code>Element</code>, <code>Attribute</code>, <code>Text</code>,
<code>CDATASection</code>, <code>Comment</code>,
<code>ProcessingInstruction</code>, or <a href='xpath.html#XPathNamespace'><code>XPathNamespace</code></a>
node. If the context node is a <code>Text</code> or a
<code>CDATASection</code>, then the context is interpreted as the
whole logical text node as seen by XPath, unless the node is
empty in which case it may not serve as the XPath context.<br>
</dd>
<dt><code class='parameter-name'>resolver</code> of type
<a href='xpath.html#XPathNSResolver'><code>XPathNSResolver</code></a></dt><dd>
The <code>resolver</code> permits translation of all
prefixes, including the <code>xml</code> namespace prefix,
within the XPath expression into appropriate <a href='glossary.html#dt-namespaceURI'>namespace URIs</a>. If this is
specified as <code>null</code>, any <a href='glossary.html#dt-namespaceprefix'>namespace prefix</a> within the
expression will result in <code>DOMException</code> being
thrown with the code <code>NAMESPACE_ERR</code>.<br>
</dd>
<dt><code class='parameter-name'>type</code> of type
<code>unsigned short</code></dt><dd>
If a specific <code>type</code> is specified, then the
result will be returned as the corresponding type.<br>
For XPath 1.0 results, this must be one of the codes of the
<a href='xpath.html#XPathResult'><code>XPathResult</code></a> interface.<br>
</dd>
<dt><code class='parameter-name'>result</code> of type
<code>DOMObject</code></dt><dd>
The <code>result</code> specifies a specific result object
which may be reused and returned by this method. If this is specified
as <code>null</code>or the implementation does not reuse the specified
result, a new result object will be constructed and returned.<br>
For XPath 1.0 results, this object will be of type
<a href='xpath.html#XPathResult'><code>XPathResult</code></a>.<br>
</dd>
</dl>
</div></div> <!-- parameters -->
<div class='return'>
<b>Return Value</b>
<div class='returntable'>
<table summary='Layout table: the first cell contains
the type of the return value, the second contains a short description'
border='0'><tr><td valign='top'><p><code>DOMObject</code></p></td><td>
<p>
The result of the evaluation of the XPath expression.<br>
For XPath 1.0 results, this object will be of type
<a href='xpath.html#XPathResult'><code>XPathResult</code></a>.</td></tr></table>
</div></div> <!-- return -->
<div class='exceptions'>
<b>Exceptions</b>
<div class='exceptiontable'>
<table summary='Layout table: the first cell contains
the type of the exception, the second contains
the specific error code and a short description'
border='0'>
<tr><td valign='top'><p><a href='xpath.html#XPathException'><code>XPathException</code></a></p></td><td>
<p>INVALID_EXPRESSION_ERR: Raised if the expression is not
legal according to the rules of the
<code>XPathEvaluator</code>i<p>TYPE_ERR: Raised if the result cannot be converted to
return the specified type.</td></tr>
<tr><td valign='top'><p><code>DOMException</code></p></td><td>
<p>NAMESPACE_ERR: Raised if the expression contains
<a href='glossary.html#dt-namespaceprefix'>namespace prefixes</a>
which cannot be resolved by the specified
<a href='xpath.html#XPathNSResolver'><code>XPathNSResolver</code></a>.<p>WRONG_DOCUMENT_ERR: The Node is from a document that is
not supported by this <code>XPathEvaluator</code>.<p>NOT_SUPPORTED_ERR: The Node is not a type permitted as an
XPath context node or the request type is not permitted by this
<code>XPathEvaluator</code>.</td></tr>
</table>
</div></div> <!-- exceptions -->
</div> <!-- method -->
</dd>
</dl></dd>
</dl></dd>
<dt><b>Interface <i><a name='XPathExpression'>XPathExpression</a></i></b></dt>
<dd>
<p>The <code>XPathExpression</code> interface represents a parsed
and resolved XPath expression.
<dl>
<dt><br><b>IDL Definition</b></dt>
<dd>
<div class='idl-code'>
<pre>
interface <a class='noxref' href='xpath.html#XPathExpression'>XPathExpression</a> {
DOMObject <a class='noxref' href='xpath.html#XPathExpression-evaluate'>evaluate</a>(in Node contextNode,
in unsigned short type,
in DOMObject result)
raises(<a class='noxref' href='xpath.html#XPathException'>XPathException</a>,
DOMException);
};
</pre>
</div><br>
</dd>
<dt><b>Methods</b></dt>
<dd><dl>
<dt><code class='method-name'><a name='XPathExpression-evaluate'>evaluate</a></code></dt>
<dd>
<div class='method'>
Evaluates this XPath expression and returns a result.<div class='parameters'>
<b>Parameters</b>
<div class='paramtable'>
<dl>
<dt><code class='parameter-name'>contextNode</code> of type
<code>Node</code></dt><dd>
The <code>context</code> is context node for the evaluation
of this XPath expression.<br>
If the XPathEvaluator was obtained
by casting the <code>Document</code> then this must be owned by
the same document and must be a <code>Document</code>,
<code>Element</code>, <code>Attribute</code>, <code>Text</code>,
<code>CDATASection</code>, <code>Comment</code>,
<code>ProcessingInstruction</code>, or <a href='xpath.html#XPathNamespace'><code>XPathNamespace</code></a>
node.<br>
If the context node is a <code>Text</code> or a
<code>CDATASection</code>, then the context is interpreted as the
whole logical text node as seen by XPath, unless the node is
empty in which case it may not serve as the XPath context.<br>
</dd>
<dt><code class='parameter-name'>type</code> of type
<code>unsigned short</code></dt><dd>
If a specific <code>type</code> is specified, then the
result will be coerced to return the specified type relying
on XPath conversions and fail if the desired coercion is not
possible. This must be one of the type codes of
<a href='xpath.html#XPathResult'><code>XPathResult</code></a>.<br>
</dd>
<dt><code class='parameter-name'>result</code> of type
<code>DOMObject</code></dt><dd>
The <code>result</code> specifies a specific result object
which may be reused and returned by this method. If this is specified
as <code>null</code>or the implementation does not reuse the specified
result, a new result object will be constructed and returned.<br>
For XPath 1.0 results, this object will be of type
<a href='xpath.html#XPathResult'><code>XPathResult</code></a>.<br>
</dd>
</dl>
</div></div> <!-- parameters -->
<div class='return'>
<b>Return Value</b>
<div class='returntable'>
<table summary='Layout table: the first cell contains
the type of the return value, the second contains a short description'
border='0'><tr><td valign='top'><p><code>DOMObject</code></p></td><td>
<p>
The result of the evaluation of the XPath expression.<br>
For XPath 1.0 results, this object will be of type
<a href='xpath.html#XPathResult'><code>XPathResult</code></a>.</td></tr></table>
</div></div> <!-- return -->
<div class='exceptions'>
<b>Exceptions</b>
<div class='exceptiontable'>
<table summary='Layout table: the first cell contains
the type of the exception, the second contains
the specific error code and a short description'
border='0'>
<tr><td valign='top'><p><a href='xpath.html#XPathException'><code>XPathException</code></a></p></td><td>
<p>TYPE_ERR: Raised if the result cannot be converted to
return the specified type.</td></tr>
<tr><td valign='top'><p><code>DOMException</code></p></td><td>
<p>WRONG_DOCUMENT_ERR: The Node is from a document that is
not supported by the XPathEvaluator that created this
<code>XPathExpression</code>.<p>NOT_SUPPORTED_ERR: The Node is not a type permitted as an
XPath context node or the request type is not permitted by this
<code>XPathExpression</code>.</td></tr>
</table>
</div></div> <!-- exceptions -->
</div> <!-- method -->
</dd>
</dl></dd>
</dl></dd>
<dt><b>Interface <i><a name='XPathNSResolver'>XPathNSResolver</a></i></b></dt>
<dd>
<p>The <code>XPathNSResolver</code> interface permit
<code>prefix</code> strings in the expression to be properly bound to
<code>namespaceURI</code> strings. <a href='xpath.html#XPathEvaluator'><code>XPathEvaluator</code></a> can
construct an implementation of <code>XPathNSResolver</code> from a
node, or the interface may be implemented by any application.
<dl>
<dt><br><b>IDL Definition</b></dt>
<dd>
<div class='idl-code'>
<pre>
interface <a class='noxref' href='xpath.html#XPathNSResolver'>XPathNSResolver</a> {
DOMString <a class='noxref' href='xpath.html#XPathNSResolver-lookupNamespaceURI'>lookupNamespaceURI</a>(in DOMString prefix);
};
</pre>
</div><br>
</dd>
<dt><b>Methods</b></dt>
<dd><dl>
<dt><code class='method-name'><a name='XPathNSResolver-lookupNamespaceURI'>lookupNamespaceURI</a></code></dt>
<dd>
<div class='method'>
Look up the <a href='glossary.html#dt-namespaceURI'>namespace
URI</a> associated to the given <a href='glossary.html#dt-namespaceprefix'>namespace prefix</a>. The
XPath evaluator must never call this with a <code>null</code> or
empty argument, because the result of doing this is undefined.<div class='parameters'>
<b>Parameters</b>
<div class='paramtable'>
<dl>
<dt><code class='parameter-name'>prefix</code> of type
<code>DOMString</code></dt><dd>
The prefix to look for.<br>
</dd>
</dl>
</div></div> <!-- parameters -->
<div class='return'>
<b>Return Value</b>
<div class='returntable'>
<table summary='Layout table: the first cell contains
the type of the return value, the second contains a short description'
border='0'><tr><td valign='top'><p><code>DOMString</code></p></td><td>
<p>
Returns the associated <a href='glossary.html#dt-namespaceURI'>namespace URI</a> or
<code>null</code> if none is found.</td></tr></table>
</div></div> <!-- return -->
<div><b>No Exceptions</b></div>
</div> <!-- method -->
</dd>
</dl></dd>
</dl></dd>
<dt><b>Interface <i><a name='XPathResult'>XPathResult</a></i></b></dt>
<dd>
<p>The <code>XPathResult</code> interface represents the result
of the evaluation of an XPath 1.0 expression within the context
of a particular node. Since
evaluation of an XPath expression can result in various result
types, this object makes it possible to discover and manipulate
the type and value of the result.
<dl>
<dt><br><b>IDL Definition</b></dt>
<dd>
<div class='idl-code'>
<pre>
interface <a class='noxref' href='xpath.html#XPathResult'>XPathResult</a> {
// XPathResultType
const unsigned short <a class='noxref' href='xpath.html#XPathResult-ANY-TYPE'>ANY_TYPE</a> = 0;
const unsigned short <a class='noxref' href='xpath.html#XPathResult-NUMBER-TYPE'>NUMBER_TYPE</a> = 1;
const unsigned short <a class='noxref' href='xpath.html#XPathResult-STRING-TYPE'>STRING_TYPE</a> = 2;
const unsigned short <a class='noxref' href='xpath.html#XPathResult-BOOLEAN-TYPE'>BOOLEAN_TYPE</a> = 3;
const unsigned short <a class='noxref' href='xpath.html#XPathResult-UNORDERED-NODE-ITERATOR-TYPE'>UNORDERED_NODE_ITERATOR_TYPE</a> = 4;
const unsigned short <a class='noxref' href='xpath.html#XPathResult-ORDERED-NODE-ITERATOR-TYPE'>ORDERED_NODE_ITERATOR_TYPE</a> = 5;
const unsigned short <a class='noxref' href='xpath.html#XPathResult-UNORDERED-NODE-SNAPSHOT-TYPE'>UNORDERED_NODE_SNAPSHOT_TYPE</a> = 6;
const unsigned short <a class='noxref' href='xpath.html#XPathResult-ORDERED-NODE-SNAPSHOT-TYPE'>ORDERED_NODE_SNAPSHOT_TYPE</a> = 7;
const unsigned short <a class='noxref' href='xpath.html#XPathResult-ANY-UNORDERED-NODE-TYPE'>ANY_UNORDERED_NODE_TYPE</a> = 8;
const unsigned short <a class='noxref' href='xpath.html#XPathResult-FIRST-ORDERED-NODE-TYPE'>FIRST_ORDERED_NODE_TYPE</a> = 9;
readonly attribute unsigned short <a class='noxref' href='xpath.html#XPathResult-resultType'>resultType</a>;
readonly attribute double <a class='noxref' href='xpath.html#XPathResult-numberValue'>numberValue</a>;
// raises(<a class='noxref' href='xpath.html#XPathException'>XPathException</a>) on retrieval
readonly attribute DOMString <a class='noxref' href='xpath.html#XPathResult-stringValue'>stringValue</a>;
// raises(<a class='noxref' href='xpath.html#XPathException'>XPathException</a>) on retrieval
readonly attribute boolean <a class='noxref' href='xpath.html#XPathResult-booleanValue'>booleanValue</a>;
// raises(<a class='noxref' href='xpath.html#XPathException'>XPathException</a>) on retrieval
readonly attribute Node <a class='noxref' href='xpath.html#XPathResult-singleNodeValue'>singleNodeValue</a>;
// raises(<a class='noxref' href='xpath.html#XPathException'>XPathException</a>) on retrieval
readonly attribute boolean <a class='noxref' href='xpath.html#XPathResult-invalid-iterator-state'>invalidIteratorState</a>;
readonly attribute unsigned long <a class='noxref' href='xpath.html#XPathResult-snapshot-length'>snapshotLength</a>;
// raises(<a class='noxref' href='xpath.html#XPathException'>XPathException</a>) on retrieval
Node <a class='noxref' href='xpath.html#XPathResult-iterateNext'>iterateNext</a>()
raises(<a class='noxref' href='xpath.html#XPathException'>XPathException</a>,
DOMException);
Node <a class='noxref' href='xpath.html#XPathResult-snapshotItem'>snapshotItem</a>(in unsigned long index)
raises(<a class='noxref' href='xpath.html#XPathException'>XPathException</a>);
};
</pre>
</div><br>
</dd>
<dt><b>Definition group <i><a name='XPathResultType'>XPathResultType</a></i></b></dt>
<dd><p>An integer indicating what type of result this is.<p>If a specific <code>type</code> is specified, then the
result will be returned as the corresponding type, using
<a class='normative' href='http://www.w3.org/TR/1999/REC-xpath-19991116#section-Expressions'><em>XPath type
conversions</em></a> where required and possible.<dl>
<dt><b>Defined Constants</b></dt>
<dd><dl>
<dt><a name='XPathResult-ANY-TYPE'><code class='constant-name'>ANY_TYPE</code></a></dt><dd>
This code does not represent a specific type. An
evaluation of an XPath expression will never produce this
type. If this type is requested, then the evaluation
returns whatever type naturally results from evaluation of
the expression. <br>
If the natural result is a node
set when <code>ANY_TYPE</code> was requested, then
<code>UNORDERED_NODE_ITERATOR_TYPE</code> is always the
resulting type. Any other representation of a node set
must be explicitly requested.</dd>
<dt><a name='XPathResult-ANY-UNORDERED-NODE-TYPE'><code class='constant-name'>ANY_UNORDERED_NODE_TYPE</code></a></dt><dd>
The result is a <a class='normative' href='http://www.w3.org/TR/1999/REC-xpath-19991116#node-sets'><em>node set</em></a> as defined
by [<cite><a class='noxref normative' href='references.html#XPath10'>XPath 1.0</a></cite>] and will be accessed as a single
node, which may be <code>null</code>if the node set is empty. Document
modification does not invalidate the node, but may mean that
the result node no longer corresponds to the current
document. This is a convenience that permits optimization
since the implementation can stop once any node in
the resulting set has been found.<br>
If there is more
than one node in the actual result, the single node returned
might not be the first in document order.</dd>
<dt><a name='XPathResult-BOOLEAN-TYPE'><code class='constant-name'>BOOLEAN_TYPE</code></a></dt><dd>
The result is a <a class='normative' href='http://www.w3.org/TR/1999/REC-xpath-19991116#booleans'><em>boolean</em></a> as defined
by [<cite><a class='noxref normative' href='references.html#XPath10'>XPath 1.0</a></cite>]. Document modification does not
invalidate the boolean, but may mean that reevaluation
would not yield the same boolean.</dd>
<dt><a name='XPathResult-FIRST-ORDERED-NODE-TYPE'><code class='constant-name'>FIRST_ORDERED_NODE_TYPE</code></a></dt><dd>
The result is a <a class='normative' href='http://www.w3.org/TR/1999/REC-xpath-19991116#node-sets'><em>node set</em></a> as defined
by [<cite><a class='noxref normative' href='references.html#XPath10'>XPath 1.0</a></cite>] and will be accessed as a single
node, which may be <code>null</code> if the node set is
empty. Document modification does not invalidate the node,
but may mean that the result node no longer corresponds to
the current document. This is a convenience that permits
optimization since the implementation can stop once the
first node in document order of the resulting set has been
found.<br>
If there are more than one node in the actual
result, the single node returned will be the first in
document order.</dd>
<dt><a name='XPathResult-NUMBER-TYPE'><code class='constant-name'>NUMBER_TYPE</code></a></dt><dd>
The result is a <a class='normative' href='http://www.w3.org/TR/1999/REC-xpath-19991116#numbers'><em>number</em></a> as defined by
[<cite><a class='noxref normative' href='references.html#XPath10'>XPath 1.0</a></cite>]. Document modification does not
invalidate the number, but may mean that reevaluation
would not yield the same number.</dd>
<dt><a name='XPathResult-ORDERED-NODE-ITERATOR-TYPE'><code class='constant-name'>ORDERED_NODE_ITERATOR_TYPE</code></a></dt><dd>
The result is a node set as defined by [<cite><a class='noxref normative' href='references.html#XPath10'>XPath 1.0</a></cite>] that will be accessed iteratively, which
will produce document-ordered nodes. Document
modification invalidates the iteration.</dd>
<dt><a name='XPathResult-ORDERED-NODE-SNAPSHOT-TYPE'><code class='constant-name'>ORDERED_NODE_SNAPSHOT_TYPE</code></a></dt><dd>
The result is a <a class='normative' href='http://www.w3.org/TR/1999/REC-xpath-19991116#node-sets'><em>node set</em></a> as
defined by [<cite><a class='noxref normative' href='references.html#XPath10'>XPath 1.0</a></cite>] that will be accessed
as a snapshot list of nodes that will be in original
document order. Document modification does not invalidate
the snapshot but may mean that reevaluation would not
yield the same snapshot and nodes in the snapshot may have
been altered, moved, or removed from the document.</dd>
<dt><a name='XPathResult-STRING-TYPE'><code class='constant-name'>STRING_TYPE</code></a></dt><dd>
The result is a <a class='normative' href='http://www.w3.org/TR/1999/REC-xpath-19991116#strings'><em>string</em></a> as defined by
[<cite><a class='noxref normative' href='references.html#XPath10'>XPath 1.0</a></cite>]. Document modification does not
invalidate the string, but may mean that the string no
longer corresponds to the current document.</dd>
<dt><a name='XPathResult-UNORDERED-NODE-ITERATOR-TYPE'><code class='constant-name'>UNORDERED_NODE_ITERATOR_TYPE</code></a></dt><dd>
The result is a <a class='normative' href='http://www.w3.org/TR/1999/REC-xpath-19991116#node-sets'><em>node set</em></a> as
defined by [<cite><a class='noxref normative' href='references.html#XPath10'>XPath 1.0</a></cite>] that will be accessed
iteratively, which may not produce nodes in a particular
order. Document modification invalidates the
iteration.<br>
This is the default type returned if the result is a
node set and <code>ANY_TYPE</code> is requested.</dd>
<dt><a name='XPathResult-UNORDERED-NODE-SNAPSHOT-TYPE'><code class='constant-name'>UNORDERED_NODE_SNAPSHOT_TYPE</code></a></dt><dd>
The result is a <a class='normative' href='http://www.w3.org/TR/1999/REC-xpath-19991116#node-sets'><em>node set</em></a> as
defined by [<cite><a class='noxref normative' href='references.html#XPath10'>XPath 1.0</a></cite>] that will be accessed
as a snapshot list of nodes that may not be in a
particular order. Document modification does not
invalidate the snapshot but may mean that reevaluation
would not yield the same snapshot and nodes in the
snapshot may have been altered, moved, or removed from the
document.</dd>
</dl>
</dd></dl>
</dd>
<dt><b>Attributes</b></dt>
<dd><dl>
<dt><code class='attribute-name'><a name='XPathResult-booleanValue'>booleanValue</a></code> of type <code>boolean</code>, readonly</dt>
<dd>The value of this boolean result.<br>
<div class='exceptions'>
<b>Exceptions on retrieval</b>
<div class='exceptiontable'>
<table summary='Layout table: the first cell contains
the type of the exception, the second contains
the specific error code and a short description'
border='0'>
<tr><td valign='top'><p><a href='xpath.html#XPathException'><code>XPathException</code></a></p></td><td>
<p>TYPE_ERR: raised if <code>resultType</code> is not <code>BOOLEAN_TYPE</code>.</td></tr>
</table>
</div></div> <!-- exceptions -->
</dd>
<dt><code class='attribute-name'><a name='XPathResult-invalid-iterator-state'>invalidIteratorState</a></code> of type <code>boolean</code>, readonly</dt>
<dd>Signifies that the iterator has become invalid.
True if <code>resultType</code> is
<code>UNORDERED_NODE_ITERATOR_TYPE</code> or
<code>ORDERED_NODE_ITERATOR_TYPE</code> and the
document has been modified since this result was
returned.<br>
</dd>
<dt><code class='attribute-name'><a name='XPathResult-numberValue'>numberValue</a></code> of type <code>double</code>, readonly</dt>
<dd>The value of this number result. If the native double type of the DOM binding does
not directly support the exact IEEE 754 result of the XPath expression, then it is up to
the definition of the binding to specify how the XPath number is converted to the
native binding number.<br>
<div class='exceptions'>
<b>Exceptions on retrieval</b>
<div class='exceptiontable'>
<table summary='Layout table: the first cell contains
the type of the exception, the second contains
the specific error code and a short description'
border='0'>
<tr><td valign='top'><p><a href='xpath.html#XPathException'><code>XPathException</code></a></p></td><td>
<p>TYPE_ERR: raised if <code>resultType</code> is not <code>NUMBER_TYPE</code>.</td></tr>
</table>
</div></div> <!-- exceptions -->
</dd>
<dt><code class='attribute-name'><a name='XPathResult-resultType'>resultType</a></code> of type <code>unsigned short</code>, readonly</dt>
<dd>A code representing the type of this result, as defined
by the type constants.<br>
</dd>
<dt><code class='attribute-name'><a name='XPathResult-singleNodeValue'>singleNodeValue</a></code> of type <code>Node</code>, readonly</dt>
<dd>The value of this single node result, which may be <code>null</code>.<br>
<div class='exceptions'>
<b>Exceptions on retrieval</b>
<div class='exceptiontable'>
<table summary='Layout table: the first cell contains
the type of the exception, the second contains
the specific error code and a short description'
border='0'>
<tr><td valign='top'><p><a href='xpath.html#XPathException'><code>XPathException</code></a></p></td><td>
<p>TYPE_ERR: raised if <code>resultType</code> is not
<code>ANY_UNORDERED_NODE_TYPE</code> or
<code>FIRST_ORDERED_NODE_TYPE</code>.</td></tr>
</table>
</div></div> <!-- exceptions -->
</dd>
<dt><code class='attribute-name'><a name='XPathResult-snapshot-length'>snapshotLength</a></code> of type <code>unsigned long</code>, readonly</dt>
<dd>The number of nodes in the result snapshot. Valid values
for snapshotItem indices are <code>0</code> to
<code>snapshotLength-1</code> inclusive.<br>
<div class='exceptions'>
<b>Exceptions on retrieval</b>
<div class='exceptiontable'>
<table summary='Layout table: the first cell contains
the type of the exception, the second contains
the specific error code and a short description'
border='0'>
<tr><td valign='top'><p><a href='xpath.html#XPathException'><code>XPathException</code></a></p></td><td>
<p>TYPE_ERR: raised if <code>resultType</code> is not
<code>UNORDERED_NODE_SNAPSHOT_TYPE</code> or
<code>ORDERED_NODE_SNAPSHOT_TYPE</code>.</td></tr>
</table>
</div></div> <!-- exceptions -->
</dd>
<dt><code class='attribute-name'><a name='XPathResult-stringValue'>stringValue</a></code> of type <code>DOMString</code>, readonly</dt>
<dd>The value of this string result.<br>
<div class='exceptions'>
<b>Exceptions on retrieval</b>
<div class='exceptiontable'>
<table summary='Layout table: the first cell contains
the type of the exception, the second contains
the specific error code and a short description'
border='0'>
<tr><td valign='top'><p><a href='xpath.html#XPathException'><code>XPathException</code></a></p></td><td>
<p>TYPE_ERR: raised if <code>resultType</code> is not <code>STRING_TYPE</code>.</td></tr>
</table>
</div></div> <!-- exceptions -->
</dd></dl></dd>
<dt><b>Methods</b></dt>
<dd><dl>
<dt><code class='method-name'><a name='XPathResult-iterateNext'>iterateNext</a></code></dt>
<dd>
<div class='method'>
Iterates and returns the next node from the node set
or <code>null</code>if there are no more nodes.
<div class='return'>
<b>Return Value</b>
<div class='returntable'>
<table summary='Layout table: the first cell contains
the type of the return value, the second contains a short description'
border='0'><tr><td valign='top'><p><code>Node</code></p></td><td>
<p>
Returns the next node.</td></tr></table>
</div></div> <!-- return -->
<div class='exceptions'>
<b>Exceptions</b>
<div class='exceptiontable'>
<table summary='Layout table: the first cell contains
the type of the exception, the second contains
the specific error code and a short description'
border='0'>
<tr><td valign='top'><p><a href='xpath.html#XPathException'><code>XPathException</code></a></p></td><td>
<p>TYPE_ERR: raised if <code>resultType</code> is not
<code>UNORDERED_NODE_ITERATOR_TYPE</code> or
<code>ORDERED_NODE_ITERATOR_TYPE</code>.</td></tr>
<tr><td valign='top'><p><code>DOMException</code></p></td><td>
<p>INVALID_STATE_ERR: The document has been mutated since the
result was returned.</td></tr>
</table>
</div></div> <!-- exceptions -->
<div><b>No Parameters</b></div>
</div> <!-- method -->
</dd>
<dt><code class='method-name'><a name='XPathResult-snapshotItem'>snapshotItem</a></code></dt>
<dd>
<div class='method'>
Returns the <code>index</code>th item in the snapshot collection.
If <code>index</code> is greater than or equal to the number of nodes
in the list, this method returns <code>null</code>. Unlike the
iterator result, the snapshot does not become invalid, but may
not correspond to the current document if it is mutated.<div class='parameters'>
<b>Parameters</b>
<div class='paramtable'>
<dl>
<dt><code class='parameter-name'>index</code> of type
<code>unsigned long</code></dt><dd>
Index into the snapshot collection.<br>
</dd>
</dl>
</div></div> <!-- parameters -->
<div class='return'>
<b>Return Value</b>
<div class='returntable'>
<table summary='Layout table: the first cell contains
the type of the return value, the second contains a short description'
border='0'><tr><td valign='top'><p><code>Node</code></p></td><td>
<p>
The node at the <code>index</code>th position in the
<code>NodeList</code>, or <code>null</code> if that is not a
valid index.</td></tr></table>
</div></div> <!-- return -->
<div class='exceptions'>
<b>Exceptions</b>
<div class='exceptiontable'>
<table summary='Layout table: the first cell contains
the type of the exception, the second contains
the specific error code and a short description'
border='0'>
<tr><td valign='top'><p><a href='xpath.html#XPathException'><code>XPathException</code></a></p></td><td>
<p>TYPE_ERR: raised if <code>resultType</code> is not
<code>UNORDERED_NODE_SNAPSHOT_TYPE</code> or
<code>ORDERED_NODE_SNAPSHOT_TYPE</code>.</td></tr>
</table>
</div></div> <!-- exceptions -->
</div> <!-- method -->
</dd>
</dl></dd>
</dl></dd>
<dt><b>Interface <i><a name='XPathNamespace'>XPathNamespace</a></i></b></dt>
<dd>
<p>The <code>XPathNamespace</code> interface is returned by
<a href='xpath.html#XPathResult'><code>XPathResult</code></a> interfaces to represent
the XPath namespace node type that DOM lacks.
There is no public constructor for this node type. Attempts to
place it into a hierarchy or a NamedNodeMap result in a
<code>DOMException</code> with the code
<code>HIERARCHY_REQUEST_ERR</code>. This node is
<a href='glossary.html#dt-readonly-node'>read only</a>, so methods or setting of attributes that would mutate
the node result in a DOMException with the code
<code>NO_MODIFICATION_ALLOWED_ERR</code>.<p>The core specification describes attributes of the
<code>Node</code> interface that are different for different
node types but does not describe <code>XPATH_NAMESPACE_NODE</code>,
so here is a description of those attributes for this node type.
All attributes of <code>Node</code> not described in this section
have a <code>null</code> or <code>false</code> value.<p><code>ownerDocument</code> matches the <code>ownerDocument</code> of the
<code>ownerElement</code> even if the element is later adopted.<p><code>nodeName</code> is always the string "<code>#namespace</code>".<p><code>prefix</code> is the prefix of the namespace
represented by the node.<p><code>localName</code> is the same as <code>prefix</code>.<p><code>nodeType</code> is equal to <code>XPATH_NAMESPACE_NODE</code>.<p><code>namespaceURI</code> is the namespace URI of the namespace
represented by the node.<p><code>nodeValue</code> is the same as <code>namespaceURI</code>.<p><code>adoptNode</code>, <code>cloneNode</code>, and
<code>importNode</code> fail on this node type by raising a
<code>DOMException</code> with the code <code>NOT_SUPPORTED_ERR</code>.<p><b>Note:</b> In future versions of the XPath specification, the definition of a
namespace node may be changed incomatibly, in which case incompatible
changes to field values may be required to implement versions beyond
XPath 1.0.</p>
<dl>
<dt><br><b>IDL Definition</b></dt>
<dd>
<div class='idl-code'>
<pre>
interface <a class='noxref' href='xpath.html#XPathNamespace'>XPathNamespace</a> : Node {
// XPathNodeType
const unsigned short <a class='noxref' href='xpath.html#XPATH_NAMESPACE_NODE'>XPATH_NAMESPACE_NODE</a> = 13;
readonly attribute Element <a class='noxref' href='xpath.html#XPathNamespace-ownerElement'>ownerElement</a>;
};
</pre>
</div><br>
</dd>
<dt><b>Definition group <i><a name='XPathNodeType'>XPathNodeType</a></i></b></dt>
<dd><p>An integer indicating which type of node this is.<p><b>Note:</b> There is currently only one type of node which is specific to
XPath. The numbers in this list must not collide with the
values assigned to core node types.</p>
<dl>
<dt><b>Defined Constants</b></dt>
<dd><dl>
<dt><a name='XPATH_NAMESPACE_NODE'><code class='constant-name'>XPATH_NAMESPACE_NODE</code></a></dt><dd>
The node is a <code>Namespace</code>.</dd>
</dl>
</dd></dl>
</dd>
<dt><b>Attributes</b></dt>
<dd><dl>
<dt><code class='attribute-name'><a name='XPathNamespace-ownerElement'>ownerElement</a></code> of type <code>Element</code>, readonly</dt>
<dd>The <code>Element</code> on which the namespace was in scope
when it was requested. This does not change on a returned
namespace node
even if the document changes such that the namespace goes out of
scope on that <a href='glossary.html#dt-element'>element</a> and this
node is no longer found there by XPath.<br>
</dd></dl></dd>
</dl></dd>
</dl>
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